We have previously tuned this & got the power up to 169kw & 320kw on the wheels:

Xcede Performance is proud to announce our Stage 3 Performance Pack that can take the stock 320i/520 N20 motor to power levels of a stock 335i. In fact we take it to 201kw & 421Nm on the wheels. A gain of 76kw and 164NM on the wheels. This translates to 230kw & 485NM at the engine. Up from the factory engine rating of 135kw & 270NM.